The foundation is responsible for the museum's cost, while the Port Authority, which owns the site, is paying for infrastructure improvements. Exactly who should pay for each component of the project has been subject to debate, and the dispute responsible for the delay partly centers over $156 million that the Port Authority says the foundation owes.

The person familiar with the construction said the museum's opening will be delayed because the Port Authority has stopped approving new construction contracts. The person spoke to The Associated Press on condition of anonymity because negotiations are ongoing.

A memorial at the trade center opened in September on the 10th anniversary of the 2001 attacks. The museum showcasing artifacts from the attacks was to open on the 11th anniversary next year.

Port Authority spokesman Steve Coleman would not comment except to say, "We are working cooperatively with New York City and the memorial on this issue."